void main() {
  ///Record类型 dart3.0新出类型 类似python的元组 tuple
  var record = ('first', a: 2, b: true, 'last');

  //打印record
  print(record);
  //打印record元素
  print(record.$1);
  print(record.a);
  print(record.b);
  print(record.$2);


  //可以通过字段名来创建定义record
  ({int a, int b}) recordAB = (a: 1, b: 2);
  print(recordAB);

}
